Double joint for steering axles in automobiles

ABSTRACT

A steering shaft universal joint assembly for motor vehicles as provided. Shaft ends are fastened against rotation in the joint, the ends being held in a housing joint adjoining the two joints with interposition of a ball joint so that the ball of the ball joint is mounted for rotation about its center point in a socket of one shaft end and is slidingly movable in a direction of the shaft axis of the other shaft end. The ball is resiliently mounted in the socket and the socket receives a slide bushing.

The invention relates to a steering shaft universal joint for motorvehicles with shaft ends fastened against rotation in the joint, theseends being held for movement in a housing joining the two joints and theshaft ends being joined together between the two joints by a ball jointso that the ball is mounted for rotation about its center point in asocket of the other shaft end and is slidingly movable in the directionof the shaft axis of the other shaft end.

One known double joint system is, for example, the double-crossuniversal joint with a ball joint disposed between the two jointcrosses. In known systems of universal joints, two joint crosses areconnected movably around the one joint cross axis by a fork on each ofthe two shaft ends and movably about the other joint axis to aconnecting housing. The centering is performed by a jointed connect-onof the two shaft ends within the connecting housing of a metal jointball at the one end of the shaft and a cylindrical socket, also ofmetal, on the other shaft end into which the joint ball enters. Theconnecting housing forms a hollow space in the interior, which creates afree space for the movement of the centering joint coupling and its sizeis proportional to the maximum angular deflection of the two shaft, endswith respect to the extended axis. The ends or stubs of the two crossesare mounted for ease of movement, for example on rolling bearings whichare situated in bores in the fork arms and in the connecting housing,respectively. The universal joint mounting with its eight bearing pointsas well as the central ball mounting requires great precision to be ableto assure easy movement of the universal joint. A slight misalignment ofthe two shaft axes within the plane of deflection can result in jammingin certain positions, which can greatly interfere with ease of movement.Moreover this also leads to undesirable wear.

To limit such disadvantages the bearings must be made with sufficientprecision, which results in greater cost of manufacture. Another knownpossibility for reducing the problem is to provide rubber-elasticmaterial as an insert around the stubs of the universal bearing suchthat the bearings will be able, with the easy elastic movement thusachieved, to adjust to the manufacturing tolerances and at the same timehave a vibration damping action. A rubber-elastic support of two to alleight universal joint stubs is restrictive when small sizes arerequired, and it is difficult and expensive to achieve.

The present invention is addressed to the problem of proposing asteering shaft universal joint in which the disadvantages of the stateof the art are eliminated. In particular, the problem consists inachieving a double joint which in addition to ease of movement is easyto install, inexpensive to make, and insensitive to productiontolerances.

The problem is solved according to the invention by providing auniversal joint of the above-noted type with one of the followingcharacterizing features; (i) the balls resiliently mounted in thesocket; and (ii) an abutment arrangement for the ball and socket isarranged on the inner wall of the housing. Additional advantageousembodiments are described herein.

According to the invention, the socket for the balls which link the twoshaft ends together is made for tumbling resiliently or springelastically. This is possible with very low fatigue and adjustablespring force. This allows a very low-cost configuration, since theequalization of tolerances by the resilient journaling needs to beperformed only once.

The ball on the one shaft extremity is preferably held in the socket ofthe other shaft extremity such that the socket for the ball isconfigured as a slide bushing and this bushing envelops the ball. Thebushing in turn is resiliently mounted in that the bushing or the socketwhich can contain the slide bushing can be fastened through resilientmeans such as springs to the one shaft extremity and to the fork,respectively, such that the socket, in case of excessive radial forces,can be pushed away by the ball in a kind of tumbling movement, until thetolerance is compensated.

The slide bushing in which the ball slides and turns is made from asliding bearing material, and such a bushing can also have a lubricantcoating. Especially suitable, however, are bushings made from a sinteredmetal on a supporting sleeve.

The bushing itself should be made such that together with the ball itforms a bearing with no free play. This is achieved by the fact that theslide bushing makes spring-elastic contact with the ball with a certainbias and thus without free play. Slotting the outer wall of the slidebushing makes this possible so that the slide bushing can breathe in theradial direction. In this manner both radial tolerances, for examplethose of the ball diameter, are absorbed and departures from tolerancesof the shaft are equalized through the resilient mounting of thebushing.

Another advantageous embodiment consists in the fact that a plasticguide is applied to the ball of the joint, and then the plastic guideitself slides in the slide bushing or the cylindrical socket. In thiscase it is possible to manufacture the bushing or the socket evenwithout any special bearing material. The bearing bushing can even beomitted and the plastic part holding the ball then glides with directguidance in the bearing sleeve which is resiliently mounted for tumblingmovement.

In universal joint systems especially of the kind mentioned above it isfurthermore important that, when the joint is assembled, a guide meansis present which brings the ball joint together in a selective manner,and furthermore that in extreme-end positions of the joint, which do notcorrespond to normal operations, a defined abutment is provided forsafety reasons. By designing the junction housing accordingly in theinternal area with corresponding surrounding abutment surfaces this canbe established. Care must be taken that especially the tumbler socketwhich in some cases bears the bushing will first engage the abutment inthe extreme position and only then contact the ball of the joint at asecond abutment surface. This assures, especially in the uninstalledcondition, that contact in the extreme position is cushioned. This kindof abutment definition is especially suitable for the present resilientball joint bearing according to the invention, but it can also be usedto advantage in other universal joints without resilient ball jointbearing.

Other embodiments of cross joints are also suitable for universal jointsystems. If, for example, especially great ease of movement and uniformmotion are required, the double joint is advantageously made with auniversal joint, also called a constant velocity joint, especially ofthe constant speed fixed link type. Between the two joints, which arejoined together by a housing, the ball joint is again arranged with theresilient mounting, so that the shaft extremities are mounted forflexural movement through the two joints. Constant velocity joints aremanufactured as “Löbro-Gelenke” by Löhr & Bromkamp GmbH, DE 6050Offenbach.

THE INVENTION SHALL NOW BE DESCRIBED WITH THE AID OF EMBODIMENTS ANDDIAGRAMMATIC FIGURES, WHEREIN:

FIG. 1 shows schematically and in section an embodiment according to theinvention of a steering shaft double-cross universal joint.

FIG. 2 shows schematically and in section another embodiment accordingto the invention of a steering shaft double-cross universal jointrotated 90° and with abutment means to limit deflection.

FIG. 3 a shows schematically a modification of the bearing system.

FIG. 3 b shows schematically and in sections, an enlargement accordingto FIG. 2, of another variable of the resilient bearing system of thetumbler sleeve with bushing.

FIG. 4 shows schematically and in section another variant of theresilient bearing system with a flanged tumbler sleeve.

FIG. 5 shows schematically and in section another variant of theresilient bearing system with free play compensating spring fingers.

FIG. 5 a shows schematically and in section a spring finger according toFIG. 5.

FIG. 6 shows schematically and in section an additional free playcompensating variant, also with a plastic sleeve of adjustable diameterbetween the tumbler socket and the slide bushing to compensate fortolerances and wear.

FIG. 7 shows schematically and in section another variant with a plasticfrictional guiding means held on the ball and the tumbler socketconfigured as a slide bushing.

FIG. 8 shows schematically and in section an embodiment corresponding toFIG. 7 with the tumbler socket configured as a spring adjusting to zerofree play for the plastic frictional guiding means.

FIG. 8 a shows schematically and in section the tumbler socket accordingto FIG. 8.

FIG. 8 b shows a detail of FIG. 8 in section and enlarged.

FIG. 9 a shows schematically and in section another embodiment of aplastic frictional guiding means with plastic spring, in the uninstalledstate.

FIG. 9 b shows schematically and in section the plastic frictionalguiding means with plastic spring corresponding to FIG. 9 a.

FIG. 10 a schematically shows in cross-section, a plastic guideaccording to FIG. 9, shown in an installed position

FIG. 10 b schematically and in a longitudinal cross-section, a plasticguiding means according to FIG. 9, also in an installed condition.

A steering shaft double-cross universal joint according to the inventionis represented in FIGS. 1 and 2. The joint consists of a tubular dualfork coupling case 8 in which two joint crosses 9 are mounted formovement. The shaft ends 1 and 2 are jointed on one another by means ofthe forks 4 and 6 which are journaled on the joint crosses 9, and bymeans of a ball joint. The ball joint includes a ball 5 mounted to oneshaft end 1, 2 and a socket 7 mounted to the other shaft end 1, 2. Theball 5 is resiliently mounted for rotation about its center point in thesocket 7 and is slidingly moveable in the direction of the shaft axis ofthe other shaft end 1, 2. Bellows can protect the joint against dirt.

The socket 7 is configured as a sliding sleeve or accommodates acylindrical bushing which is coated either with an antifrictionmaterial, for example an antifriction metal, such as preferably asintered metal with supporting sleeve. To permit an appropriateequalization of tolerances, the socket 7 is mounted resiliently to thefork 6, so as to be deflected in a tumbling manner with respect to theshaft axis 3 by a certain transverse force. The bias of the plate spring31 is selected such that a sufficiently great restoring force is presentand the tolerance equalization is assured combined with ease ofoperation.

In FIG. 2 there is shown in cross section a joint rotated 90 degrees, inwhich the forks 4 and 6 are represented at the shaft ends 1 and 2. Thelatter can be movably inserted, as mentioned, in the crosses 9 on thecasing 8, which can be tubular, for example. In the central inner areaof the casing the end abutments 13 and 14 are represented, which are inthe form of annular raised portions and are helpful until the joint isassembled, and serve simultaneously as safety abutments in extremeterminal positions of the joint. The abutment surfaces 13 and 14 areconfigured such that the socket 7 when in the extreme position withrespect to the ball 5 will first make movement-limiting contact with theabutment 13.

The bushing 11, which is shown in cross section in FIG. 3, isadvantageously interrupted by a slot 15 so that the bushing can breatheradially and can be fitted with bias onto the ball 5. This brings itabout that the bushing 11 rotates and/or slides on the ball 5 withoutclearance. The slot 15 can be created either lengthwise of the shaft orin spiral form or in any other way that interrupts the wall.

Another possibility for increasing the springing action of the bushing11 or provide for additional damping consists, in addition to thetumbler bearing on the fork 6, in applying a rubber-elastic materialbetween the bushing 11 and the socket 7.

In FIG. 3 is shown how the socket 7 can be held on the fork with bias asa tumbler socket 7 by springs 31. On account of the great bias forcethat is to be applied and the small amount of space available, platesprings are preferred. They furthermore are less expensive. Anotherappropriate spring mounting is possible by the use of rubber-elastic 31P(FIG. 3 a) pads which can be in annular form, for example, held betweenmetal disks 31D. This can be done if necessary in a layeredconfiguration.

In FIG. 3 it is furthermore to be seen that the plate springs 31 areheld advantageously in an annular chamber 34 which is formed at the endof fork 6 at a shaft end. In FIG. 3, the tumbler guide means 7, 30, isprovided with a flange 33 which serves as a spring abutment and is urgedagainst another flange 41 configured as a holding lip or claw, so that,in the rest position, it is aligned axially with the shaft axis. Theflange 41 furthermore holds the friction bearing in an axial position.

In FIG. 3 b, another variant of the tumbler sleeve mounting is shown;here the tumbler sleeve 7, 30 is urged by a spring or springs 31abutting flange 33 on the tumbler aide against the flange 35 on the forkside. The spring 31 in that case thrust against the flange 41 formingthe chamber 34; for assembly they are held on the socket 7. In thismanner, as shown in FIGS. 3 and 3 b, the tumbler sleeve 7, 30 (or thesocket 7, 30) is resiliently pivotably mounted to the other shaft endand resiliently supported in the axial direction, so that the tumblersleeve 7, 30 can tumble resiliently about the shaft axis when subjectedto a radial force. The bushing 11 is advantageously affixed to thetumbler socket 7 by holding means 32, 32.2. Advantageously this isaccomplished by rim 82, at least on the side of bushing 11 remote fromthe fork 6. The hook of the rim 32 should overlap the bushing 11 atleast to the extent that, when wear occurs and free play results it willnot drop out. At the other end of the bushing 11 a retaining projection32.1 can be provided which holds the bushing 11 in place in the otheraxial direction.

Additional possibilities for the bearing are represented in FIG. 4. Inthe upper half of the figure a rim 32.2 clutches the fork 6 on the sidefacing away from the ball of a projection 42. The springs 31 are heldbetween the front side of the projection 42 and a rim of the bushing 11forming an annular chamber 34.

As represented in FIGS. 5 and 5 a, the bushing 11 can additionally beheld resiliently by spring fingers 38, the latter being provided orformed on the tumbler sleeve 30. This provides additional compensationfor tolerances.

The use of a preferably adapting plastic sleeve 36, between the bushing11 and the tumbler guide, according to FIG. 6, additionally permits thefree play of the bearing to be held closer to zero by compensating forwear and it simplifies assembly. The tapering shape of the plasticsleeve 36 and tumble guide 7,30 additionally improves adjustment to zerofree play. The plastic sleeve can be shaped in an appropriate manner,preferably tapering and likewise slotted, so that the bushing 11 isfixed, for example by lugs which overlap the bushing 11 at itsextremity. It is advantageous if a spring 31.1 urges the taperadaptably. A suitable plastic is chiefly POM, but also PA, PA and GF.

Another possibility for simplifying the bearing, as shown in FIG. 7,consists in omitting the metal bushing 11 and providing a rotatoryplastic friction bearing 37 on the ball, which is held for axial slidingmovement in the tumbler guide 30, 7. An additional slight compensationof free play can be accomplished by spring lips which rub with pressureon the ball surface in the deflected joint and axially displace theplastic bearing in play.

As represented in FIGS. 8, 8 a and 8 b, the system can be furtherimproved by making the cylindrical tumbler guide 7, 30, spring-elasticin its wall area, and having it surround the plastic sliding guide 37without clearance and even compensating in case of wear. This is easy toaccomplish by appropriate choice of a material and by providing slotswhich interrupt the wall in some areas and thus form resilient springfingers 38. This embodiment can be made at especially low cost and makesthe joint easy to assemble. Additional advantages are the large-surfacecontact with the ball and thus less wear, good damping of shocks and agreat selection of appropriate materials such as POM, PA, PA + GF, aswell as plastic and carbon fiber materials which have particularly goodlubricant properties. POM in this case is especially suitable and low incost. In addition, slots in the central area of the sliding guide 37 canbe shaped to form spring lips 37.1 in order to surround the ball 5resiliently with still less clearance.

The guide 37 is preferably injection molded directly into the ball 5.The variant in FIGS. 9 b and 9 a shows in longitudinal and cross sectionan additional preferred possibility for a damping compensation of freeplay in the unbiased state. The plastic sliding guide 37 is provided inits outer wall area with a plastic spring 39, which permits slidingwithout free play under bias V. The spring 39 is preferably made in onepiece with the plastic guide 37, the spring being preferably slotted 40so that it can breathe radially and being in contact with the insidesurface of the tumbler guide 30 in a wear and tolerance equalizingmanner. In FIG. 10 the same plastic sliding guide as in FIG. 9 is shownin the installed state. The tolerance gaps A, B, which the spring spanswith respect to the tumbler guide 30, are shown schematically.

The features of novelty which characterize the invention are pointed outwith particularity in the claims annexed to and forming a part of thisdisclosure and are entirely based on the Swiss priority application.

1. Steering shaft universal double joint for motor vehicles with shaftends fastened against rotation in the universal double joint, these endsbeing held for movement in a housing joining two single joints and theshaft ends being joined together between the two single joints by a balljoint so that a ball, connected to one of the shaft ends, is mounted forrotation about a center point of the ball in a socket of the other shaftend and is slidingly movable in the direction of the shaft axis of theother shaft end, wherein the socket is resiliently pivotably mounted tothe other shaft end.
 2. Universal double joint according to claim 1,further comprising: a slide bushing held by the socket, the slidebushing being enveloped at least partially by the socket and beingdisposed between the ball and the socket.
 3. Universal double jointaccording to claim 2, wherein the resiliently pivotably mounting of thesocket in the other shaft end includes metal springs.
 4. Universaldouble joint according to claim 3, wherein the metal springs are platesprings, and wherein the plate springs are biased against the socket, sothat the shaft axis, when in the unstressed position, is aligned withthe axis of the socket.
 5. Universal double joint according to claim 3,wherein the metal springs include plate springs.
 6. Universal doublejoint according to claim 2, wherein the bushing consists of a sinteredmetal.
 7. Universal double joint according to claim 2, wherein thebushing is slotted such that the bushing is resiliently movable in aradial direction.
 8. Universal double joint according to claim 2,wherein the bushing envelops the ball in a wear- andtolerance-equalizing manner in any working position, the bushing beinginstalled in the socket with about zero clearance.
 9. Universal doublejoint according to claim 2, wherein at the other shaft end, an annularchamber is formed to accommodate a pre-biased spring disposed between afirst flange on the shaft end side and a second flange on the socket, sothat the socket can tumble resiliently about the shaft axis in case ofradial action by a force.
 10. Universal double joint according to claim2, wherein the bushing is held in an axial direction at at least one endby the socket by a rim or by claws.
 11. Universal double joint accordingto claim 2, wherein, between the bushing and the socket, a plasticsleeve, is provided, and the plastic sleeve is under pressure applied bya spring.
 12. Universal double joint according to claim 2, wherein thesocket is resiliently supported in the axial direction.
 13. Universaldouble joint according to claim 2, wherein the slide bushing isresiliently held by the socket.
 14. Universal double joint according toclaim 1, wherein the resiliently pivotably mounting of the socket in theother shaft end includes metal springs.
 15. Universal double jointaccording to claim 1, wherein the resiliently pivotably mounting of thesocket in the other shaft end includes elastomeric spring pads. 16.Universal double joint according to claim 1, wherein a plastic slidingguide is provided between the socket and the ball such that the plasticsliding guide receives the ball for rotational movement and is carriedfor sliding movement in the axial direction by the socket, the guidebeing injection-molded directly onto the ball.
 17. Universal doublejoint according to claim 16, wherein the socket has spring-fingerstructure on its circumference and resiliently grips the plastic slidingguide between the ball and the socket.
 18. Universal double jointaccording to claim 17, wherein the plastic sliding guide is enveloped inan outer wall area by a pre-biased plastic spring which slides in thesocket, this spring having slots in its circumference, so that it canbreathe in the radial direction.
 19. Universal double joint according toclaim 16, wherein the plastic sliding guide is enveloped in an outerwall area by a pre-biased plastic spring which slides in the socket,this spring having slots in its circumference, so that it can breathe inthe radial direction.
 20. Universal double joint according to claim 1,wherein on an inner wall of the housing an abutment structure isprovided for the ball and the socket.
 21. Universal double jointaccording to claim 20, wherein the abutment structure is so configuredthat the ball and the socket define given allowable positions in allextreme joint deflections and in the case of assembly, the abutmentstructure being so configured that in case of abutment first the socketand then the ball makes contact.
 22. A steering shaft universal doublejoint for motor vehicles, comprising: two shaft ends; two single joints,each shaft end being connected to one of the joints; a housing joiningthe two single joints; and a socket and a ball joint disposed in thesocket, the shaft ends being joined together between the two singlejoints by the ball joint and socket, wherein the ball joint isassociated with one of the shaft ends and is able to rotate in thesocket and slidingly movable in the direction of the shaft axis of theother shaft end, and wherein the socket is resiliently pivotablyconnected to the other shaft end.
 23. The universal double jointaccording to claim 22, further comprising: a bushing disposed betweenthe ball joint and the socket, wherein the bushing is resilientlydisposed in the socket.
 24. The universal double joint according toclaim 23, further comprising: a spring, wherein the socket isresiliently pivotably mounted to the other shaft end using the spring,and the spring biases the socket to a position where an axis of thesocket is aligned with an axis of the other shaft end.
 25. The universaldouble joint according to claim 24, wherein the socket is resilientlysupported in the axial direction by the spring.
 26. The universal doublejoint according to claim 23, wherein the bushing is slotted such thatthe bushing is resiliently movable in a radial direction within thesocket.
 27. The universal double joint according to claim 26, whereinthe bushing envelops the ball in a wear- and tolerance-equalizingmanner, the bushing being installed in the socket with zero clearance.28. The universal double joint according to claim 22, wherein the socketis resiliently supported in the axial direction by the other shaft end.29. The universal double joint according to claim 22, furthercomprising: a slotted and tapered plastic sleeve disposed between thebushing and the socket.
 30. The universal double joint according toclaim 22, further comprising: a plastic sliding guide disposed betweenthe socket and the ball such that the plastic sliding guide receives theball for rotational movement and is carried for sliding movement in theaxial direction by the socket.
 31. The universal double joint accordingto claim 30, wherein the sliding guide is injection-molded directly ontothe ball.
 32. The universal double joint according to claim 30, whereinthe plastic sliding guide is enveloped in an outer wall area by apre-biased plastic spring which slides in the socket, the plastic springhaving slots in a circumference of the spring, so that the plasticspring can breathe in the radial direction.
 33. The universal doublejoint according to claim 22, wherein the other shaft end includes anannular chamber containing a spring disposed between a first flange onthe side of the other shaft and a second flange on the socket, so thatthe socket can tumble resiliently about the shaft axis when subjected toa radial force.